build: update c-dvar subproject
build: update c-dvar subproject

Pull in build-system and test-suite updates, to make sure we don't fail
when running the bundled tests.

Signed-off-by: David Herrmann <fb53b2ddb8d141e0cb39d7c67c2f81b6bc2eb0f7@gmail.com>

bus1/dbus-broker